diff options
| author | Pengcheng Yang <yangpc@wangsu.com> | 2019-12-30 17:54:41 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2020-01-02 15:42:28 -0800 |
| commit | c9655008e7845bcfdaac10a1ed8554ec167aea88 (patch) | |
| tree | 47f88a850061d17b1635abe37ab0d17238a479a5 | |
| parent | f7a48b68abd9b20ce1ac6298aaaa3c4d158271dd (diff) | |
tcp: fix "old stuff" D-SACK causing SACK to be treated as D-SACK
When we receive a D-SACK, where the sequence number satisfies:
undo_marker <= start_seq < end_seq <= prior_snd_una
we consider this is a valid D-SACK and tcp_is_sackblock_valid()
returns true, then this D-SACK is discarded as "old stuff",
but the variable first_sack_index is not marked as negative
in tcp_sacktag_write_queue().
If this D-SACK also carries a SACK that needs to be processed
(for example, the previous SACK segment was lost), this SACK
will be treated as a D-SACK in the following processing of
tcp_sacktag_write_queue(), which will eventually lead to
incorrect updates of undo_retrans and reordering.
Fixes: fd6dad616d4f ("[TCP]: Earlier SACK block verification & simplify access to them")
Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/ipv4/tcp_input.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 88b987ca9ebb..0238b554a1f0 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1727,8 +1727,11 @@ tcp_sacktag_write_queue(struct sock *sk, const struct sk_buff *ack_skb, } /* Ignore very old stuff early */ - if (!after(sp[used_sacks].end_seq, prior_snd_una)) + if (!after(sp[used_sacks].end_seq, prior_snd_una)) { + if (i == 0) + first_sack_index = -1; continue; + } used_sacks++; } |